The invention relates to a disk storage drive for receiving at least one storage disk having a central opening, with an outer rotor type driving motor having a rotor casing mounted by means of a shaft in a bearing system so as to rotate relative to a stator and on which can be placed the storage disk for driving by the rotor casing, as described in U.S. patent application Ser. No. 353,584, now U.S. Pat. No. 4,438,542, issued Mar. 27, 1984.
The content of this patent is incorporated herein by reference to avoid unnecessary repetition. It relates to a storage drive for receiving at least one storage disk having a central opening. The driving motor extends coaxially at least partly through the central opening of the storage disk, and means are provided for connecting the storage disk and the driving motor rotor.
One problem of the present invention is to further simplify the construction of a disk storage described in the aforementioned U.S. Pat. No. 4,438,542, while improving its operation. For example, the storage disk is to be reliably protected against undesired influencing by the magnetically active parts of the driving motor. In addition, a particularly space-saving and robust construction of the driving motor are to be achieved.
According to the invention, this first problem is solved in that at least the part of the rotor casing receiving the storage disk is made from a non-ferromagnetic material and carries the shaft directly or by means of a hub and in that a magnetic shield made from a ferromagnetic material in the form of a drawn can projects into the storage disk receiving part of the rotor casing and is connected thereto. The shielding surrounds the periphery of the magnetically active parts of the driving motor and also envelops the parts at one end. The shield has a central opening whose edge is directly radially adjacent the shaft or parts of the driving motor carrying or supporting the shaft. A rotor casing constructed in this way can be easily manufactured, and it effectively protects the magnetically sensitive storage disks, particularly magnetic hard storage disks, against magnetic stray flux emanating from the magnetically active parts of the driving motor. The shield is preferably in the form of a deep-drawn can, and the part of the rotor casing receiving the storage disk can be made from a lightweight metal by die casting.
If, in the manner described in the aforementioned U.S. Pat. No. 4,438,542, the driving motor is constructed as a brushless direct current motor with a permanent magnet rotor, then in accordance with a further development of the invention a printed circuit board with at least one rotary position detector and perhaps other electronic components for the control and regulation of the driving motor are mounted on the side of the stator remote from the closed end of the shielding can. This ensures that the rotary position detector and any further circuit components of the magnetic shielding arrangement do not interfere with the rotating parts.
Further advantageous developments of the invention also are disclosed, including features that contribute to a compact construction of the disk storage drive. In connection with disk storage drives of the present type, high demands are made on the concentricity of the storage disks. It is therefore generally necessary to machine the storage disk receiving part or to work it in some other way so that it is dimensionally true. As a result of other features of the invention, the necessary machining is reduced to a relatively small part of the circumferential surface of the storage disk receiving part and a trouble-free engagement of a storage disk on the shoulder of the storage disk receiving part is permitted.
Other features of the invention provide a robust precision mounting support for utilizing the available axial overall length for maximizing the distance between the bearings; and permit particularly large distances between the bearings where the axial installation area between a mounting or assembly flange and the end of the storage disk receiving part is limited. Installation space is available on the other side of this flange. Still other features provide for alternative solutions leading to particularly small radial runouts of the rotor; ensure a space-saving housing of the circuit board; and for solutions where importance is attached to a particularly shallow construction.
In a further development of the invention, a disk storage drive of the type disclosed in U.S. Pat. No. 4,779,165, issued Oct. 18, 1988, now U.S. Pat. No. Re. 34,412, issued Oct. 19, 1993, is considered. Some such disk storage drives have stationary shafts and a sealed off internal space within the motor.
In the construction of such data storage disk drives with stationary shafts, problems also have arisen in the following areas:
a) Achieving extremely high level of precision required for repeatable shaft runout;
b) Improving the sealing of the clean chamber; and
c) Achieving a and b within acceptable costs.
Yet another purpose of the present invention, therefore, is to provide a further development of the data storage disk drive of the above type having a stationary shaft by providing viable solutions for various combinations of the above problems, such as a and c; b and c; and a, b and c.
If the rotational position sensor device has several rotational position sensors, preferably of the type sensitive to magnetic fields, it is advantageous for these sensors to be supported on a common molded piece, especially if it is made by injection molding. The construction of the molded piece for the accommodation of several rotational position sensors in accordance with the invention simply ensures the precise mutual alignment of these sensors.
If required, the rotary position sensing arrangement can be mounted on a printed circuit board, together with any known type of commutation electronics. This printed circuit board can be supported on a fixed flange or bracket which is, in turn, connected to the shaft through which the connecting leads to the rotary position sensors may be brought out.
The control arrangement, which preferably takes the form of a control magnet can be mounted on the outside of a cover which seals off the space inside the motor. This cover may preferably serve as a bearing bracket as well. The control arrangement, however, also can be mounted on a part of the hub at a distance from the disk carrier stage outside the sealed internal space of the motor. A flange which serves to support the data storage disk or disks, may be connected to the remaining hub parts as one piece, or alternatively, this flange may form part of the cover which seals off the internal space of the motor.
In accordance with one variant of the present invention, at least the electric supply leads to the stator windings are brought out of the sealed internal space of the motor over a bearing support ring. This arrangement obviates the need to provide passages in the shaft to accommodate the winding connections. In yet another alternative arrangement, the rotary position sensing arrangement, together with the commutation electronics, if necessary, can both be housed in the sealed internal space of the motor with their leads and connections being brought out over the bearing support ring. In any event, none of the above arrangements requires the provision of passages formed through the stationary shaft, thus avoiding the need to weaken the shaft or to perform additional machining operations in the manufacturing thereof.
The bearing support ring can be a prefabricated component provided with recesses for the passage of the electric leads and connections. Alternatively, the aforesaid connections can be potted inside the bearing support ring.